Combined refrigerator/freezer appliances typically have two or more compartments that are refrigerated to differing temperatures, one being chilled to a temperature well below the freezing temperature of water, such as around 0° F. and the other being chilled to a below ambient temperature, which is above freezing, such as around 40° F. To chill the two different compartments to these temperatures, a refrigeration system is typically employed which includes one or two evaporator components.
In a single evaporator systems, such as those disclosed in U.S. Pat. No. 5,490,395, the evaporator is located in, or in close communication with the freezer compartment, and the evaporator is chilled to below the desired temperature for the freezer compartment. Air is circulated over the evaporator to chill the freezer compartment. To cool the refrigerator or fresh food compartment, air is ducted out of the freezer compartment and is circulated through the fresh food compartment, and then returned to the freezer compartment. A separate fan may be provided for the fresh food compartment air circulation system along with a damper for permitting or preventing the flow of sub-freezing air into the fresh food compartment.